Pneumatic regulating valve

Abstract

The invention is an improvement in a pneumatic regulating valve of the type having a main flow path and a bleed passage. In the improvement, the bleed passage is in parallel with the main flow path and regulates a downward-trending pressure at the outlet port to prevent such pressure from diminishing or from rapidly diminishing. The valve also includes a check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port. Using a constant bleed orifice to substantially pressure-balance the check valve and a small-area protrusion on the check valve to reduce contact area, the check valve exhibits very low hysteresis.

I claim: 
     
       1. In a pneumatic regulating valve having a main flow path, a bleed passage, an inlet port and an outlet port, the improvement wherein: the bleed passage is in parallel with the main flow path; for regulating a downward-trending pressure at the outlet port;   the valve includes a substantially pressure-balanced check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port; and,   the bleed passage is open, irrespective of the relationship of the pressure at the outlet port and the pressure at the inlet port to one another.   
     
     
       2. The valve of claim 1 wherein: the bleed passage includes a bleed orifice;   the check valve moves along an axis; and,   when the check valve is closed, the orifice maintains the pressure at the downstream side at a value only slightly less than the pressure at the upstream side, whereby the check valve is substantially axially pressure balanced.     
     
     
       3. The valve of claim 2 including a supply stem having an axial passage and a cavity along the bleed passage and the check valve is confined in the cavity for limited movement. 
     
     
       4. The valve of claim 3 wherein the cavity is defined in part by a first boundary surface and the bleed orifice is embodied as a groove formed in the surface. 
     
     
       5. The valve of claim 4 wherein the cavity is defined in part by a second, generally cylindrical boundary surface, the check valve is disc-like and has at least one perimeter irregularity defining a bleed passage flow clearance between the check valve and the cylindrical boundary surface. 
     
     
       6. The valve of claim 5 wherein the check valve has a plurality of perimeter irregularities spaced generally equidistant from one another whereby the check valve is substantially pressure balanced laterally. 
     
     
       7. The valve of claim 1 including a supply stem having a cavity defined in part by a first boundary surface and the check valve has a body and a protrusion extending from the body and contacting the first boundary surface whereby the check valve is substantially prevented from sticking to the first boundary surface. 
     
     
       8. The valve of claim 9 wherein the protrusion is a generally circular ridge. 
     
     
       9. The valve of claim 1 including a main valving seat and an inlet port, the bleed passage has a passage entrance and wherein: the portion of the main flow path extending from the inlet port to the main valving seat is spaced from the bleed passage entrance, whereby the regulator is made clog resistant.     
     
     
       10. The valve of claim 9 including a spring retainer having a face and wherein the face has at least one groove formed therein defining the bleed passage entrance. 
     
     
       11. The valve of claim 10 wherein the face is circular and has a pair of radial grooves formed therein and spaced about 180° apart. 
     
     
       12. In a pneumatic regulating valve having a main flow path, a bleed passage and an outlet port, the improvement wherein: the bleed passage is in parallel with the main flow path for regulating a downward-trending pressure at the outlet port;   the valve includes a substantially pressure-balanced check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port;   the check valve has an upstream side and a downstream side and both sides are in flow communication with the bleed passage;   the valve includes a supply stem having an axial passage and a cavity along the bleed passage and the check valve is confined in the cavity for limited movement;   the bleed passage includes a bleed orifice;   the cavity is defined in part by a first boundary surface and the bleed orifice is embodied as a groove formed in the surface;   the check valve moves along an axis; and,   when the check valve is closed, the orifice maintains the pressure at the downstream side at a value only slightly less than the pressure at the upstream side and thereby substantially pressure balances the check valve axially.   
     
     
       13. The valve of claim 12 wherein the cavity is defined in part by a second, generally cylindrical boundary surface, the check valve is disc-like and has at least one perimeter irregularity defining a bleed passage flow clearance between the check valve and the cylindrical boundary surface. 
     
     
       14. The valve of claim 13 wherein the check valve has a plurality of perimeter irregularities spaced generally equidistance from one another whereby the check valve is substantially pressure balanced laterally. 
     
     
       15. In a pneumatic regulating valve having a main flow path, a bleed passage and an outlet port, the improvement wherein: the bleed passage is always open and is in parallel with the main flow path for regulating a downward-trending pressure at the outlet port;   the valve includes a substantially pressure-balanced check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port; and   the valve includes a supply stem having a cavity defined in part by first boundary surface and the check valve has a body and a protruding generally circular ridge extending from the body and contacting the first boundary surface whereby the check valve is substantially prevented from sticking to the first boundary surface.   
     
     
       16. In a pneumatic regulating valve having a main flow path, a bleed passage and an outlet port, the improvement wherein: the bleed passage is in parallel with the main flow path for regulating a downward-trending pressure at the outlet port; and,   the valve includes a substantially pressure-balanced check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port;   the valve includes a main valving seat, an inlet port and a spring retainer having a face;   the bleed passage has a passage entrance embodied as at least one groove formed in the face;   the main flow path has a portion extending from the inlet port to the main valving seat;   the portion is spaced from the bleed passage entrance whereby the regulator is made clog resistant.   
     
     
       17. The valve of claim 16 wherein the face is circular and has a pair of radial grooves formed therein and spaced about 180°apart.